Thursday at 8pm and Bestival is deserted. A ghost town. A sunken shipwreck. The woodland trails, lakeside bars and hammocks of the ambient forest lie empty; you can sit on the bench in the marble Chinese pagoda and see not a solitary stoned soul for an hour. Out in the Port, a field dotted with abandoned boats and ships in bottles and dominated by a gigantic white steam-liner sinking into the hillside, food trailers pull down shutters and the fairground slide blinks its lights forlornly for no-one.

Hello! We've come for the summer's wildest send-off, bought this Popeye hat in accordance with the 2013 nautical theme and everything. Where is everybody? Has HMS Bestival hit a ticket sales iceberg?

Then a distant roar, the thick, muffled thump of electronic beats and realisation dawns. We've somehow wandered through the wrong entrance, into a section of Bestival that doesn't open until Friday. Follow the crowd noise, burst through the dam of security and out into the ocean of punters and Bestival 2013 is an urgent churn of pleasure-seeking abandon. Everywhere they possibly can, people are dancing. Rammed into the tiny trunk of the Wishing Tree, overlooked by a huge puffin nested in a castle turret. In the smoke from a knackered pick-up out front of the Swamp Shack, where screamo garage rockers Polio are tearing up the decrepit wooden porch. At the Wagamama take-away stall and at mobile phone charging stands, they're dancing. The crowd in the Polka Tent is perhaps the most up-for-it of any crowd there's ever been, anywhere - knee-jerking, high-kicking and elbow-spinning like crazed Cossacks while a band in home-made Egyptian pharaoh robes called King Lagoon's Flying Swordfish Band are still tapping mikes and plugging in their saxophones.

Site-wide, there's a tangible sense of mania. Post-Milton Jones, the emptied comedy tent is being used as a mating ground for sailor pigs. A grizzled Mario Brother picks litter. A man, vastly misunderstanding the deal, urinates into the Water Aid tent. "Bella! You've got to stick it up your arse or it doesn't work!" yells one young woman to her confused-looking friend, suggesting that endoscopy is Bestival's new "legal high" of choice. And there, over in the Magic Meadow, cordoned off like the Stonehenge of soul, stands the huge, inflatable head of Lionel Richie. A monstrous totem of purest surrealism, it draws awestruck throngs to its base to sing All Night Long to themselves, and dance.

There's a real feeling of clutching madly at the last beats of summer. Tomorrow, they say, the elements will try to set HMS Bestival afloat. So tonight, while it's still dry enough to pogo, they flock to the Big Top tent, the epicentre of Thursday's entertainment. Here, camp sailors parade the stage with gigantic cutlasses (saucy) to DJs dropping Justice Vs Simian. A monochrome vaudevillian clown, fronting an act called the Correspondents, prances around to a mash-up of hip-hop, electronica and the Charleston, arguably having taken the soundtrack to The Great Gatsby a little too seriously. And, at 1am, the festival's biggest cult draw takes to a stage bedecked with neon Hindu-style symbols, clad in the headdress and rainbow-speckled jacket of a Bollywood cross-dresser. In fact, MIA's first full UK gig in three years, ahead of her endlessly delayed fourth album Matangi, seems designed to emulate the tinny production and muddy vocals of 1970s Bollywood soundtracks to the point that you'd think the whole set was being mimed from some dusty reel-to-reel until Maya makes her between-song pronouncements with the same dense, echoing effect on her voice.

It acts to homogenise her global beats into one frustratingly localised reference, but it does make for an enthralling, narcotic experience and the deep-bass assault of Boyz, Bucky Done Gun and Born Free – cut short for Maya to demand "more aggro" from the crowd on the chorus chant - slice through the fug with sizzle and clout. Beside Paper Planes - which prompts a fresh run on an already rammed tent – her best songs may sound like a street full of cars honking their celebration at a South American World Cup win, but MIA still seems the most vital pan-cultural electro pioneer on the planet.

Friday dawns grey, damp, but optimistic. Bestival's spirit is notoriously buoyant and, finally launched, The Port is alive. People man the grounded lifeboats in anticipation of the forecast deluge, a security girl dances devotedly before a giant wicker merman and heads bob like bouys in a storm as Rob Da Bank takes the helm of the HMS Bestival liner for midday rave manoeuvres. In the Big Top, raucous shanty-howlers Skinny Lister are doing the hornpipe and recommending we start the day with gin and ginger. We think better of it, not wanting to watch The Flaming Lips tonight while clapped in irons.

Festival goers erect their tent at Bestival. Photograph: Yui Mok/PA

Over in the Replay tent 17-year-old Chlöe Howl, wearing what appears to be a shrunk school uniform, gets non-sea-based festivities underway with her addictive Lahndahn soul pop – all pixie seduction with a malicious undercurrent. "This is dedicated to all the wankers," she sneers sweetly as introduction to a sublime slice of spite pop attacking a coterie of guys who've screwed her over. It seems Howl has bite.

If malicious undercurrent floats your boat, here's the Wu Tang Clan, rounding the enormous anchor onto the main stage. Or at least, here's some of them. Rumour has it that RZA and Method Man fell foul of customs en route to the Isle of Wight, so it's a reduced and un-starry Wu that arrive in a flurry of energetic shouting and close-harmony self aggrandisement. They fill the gaping spaces onstage with GZA deck gymnastics, snippets of the Beatles' Come Together, a tribute to ODB in the shape of a chunk of Got Your Money and many entreaties to make some noise if we love "real hip-hop". But as virulently and thrillingly as they throw themselves into Da Mystery Of Chessboxin, Gravel Pit and C.R.E.A.M, it's impossible not to feel a twinge of disappointment.

The skies clear, HMS Bestival may have rounded the storm. Onwards, then, to Drenge.